my dad has cancer and has developed a clot in his leg which is not the dangerous one, but is very painful. he had an operation where they put plates and pins in his leg due to the cancer eating away his femur to about one inch. he is limited to small pain killers and cannot go for surgery due to chemo treatments. would he benefit from using leeches on the spot where his clot is? also his blood is thin, would this be harmful in any way?would the leeches be helpful in other parts of his body where he has cancer?